1. Field of the Invention
The invention relates to a control, data monitoring and logging system for a process tool.
2. Description of the Related Art
A process tool executes a treatment according to predetermined conditions on material to be treated. Examples are process tools for the treatment of semiconductor wafers, chemical reactors etc. A process tool typically comprises a number of devices like valves, mass flow controllers, a temperature controller providing input signals to a Thyristor Pack or Silicon Controlled Rectifier (SCR), empowering a heating element to be able to control the processing conditions like gas flows, pressure, temperature, etc. A process tool controller controls these devices. For this purpose the controller comprises a number of digital inputs and outputs and a number of analog inputs and outputs. Via the outputs, the various devices are controlled, and via the inputs, information is collected about the actual conditions in the process tool.
In general, process tools have a significant environmental impact because they consume significant amounts of gases, power, cooling water, air extraction, materials etc. For a processing plant it is important to know the total consumption of the plant in order to be able to guarantee a sufficient supply of the utilities. Furthermore, information about the time-average usage of the utilities is important from a cost point of view. And, last but not least, legal regulations increasingly require that the environmental impact of a processing plant be known.
As a first approximation, the time-average consumption of utilities can be calculated based on the specifications of the various tools and assumptions of utilization. However, the actual consumption can deviate substantially from the calculated consumption because either the specification or the assumptions or both can deviate from the actual situation. Therefore, in the art the consumption is measured and monitored.
In the art, the central supply systems for the various utilities are provided with consumption measuring devices and with a monitoring and data logging system so that the consumption on the plant level is known. However, this information is very general and does not provide the possibility of a more detailed analysis of where the utilities are going, which processing tool is consuming more than others, and where in the plant the most important savings could be achieved. For these purposes, information about the consumption of all the individual processing tools would be required. This information can be obtained according to the prior art by providing the utilities supply systems with consumption measuring devices at each individual tap point and monitoring and logging the consumption by a central monitoring and data logging system. However, this would make the utilities supply systems very complicated. It is the object of the present invention to provide means and a method to monitor and report the utility consumption for each tool while omitting the disadvantages outlined above.